Process of producing theine-free tea



Patented Apr-2, 1935 t I UNITED STATES PATENT orrlca raoonss or d i zze rnnmnf-mnn Theodor Grethe, Hambur Germany No Drawing. Application June 1, 1932, Serial No.' 614,848. In Germany June 3, 1931 4 Claims. (Cl. 99-11) The suggestion has already been made to proride CH2C12, chloroform, benzole, etc. or a mixduce a tea free from theine by extracting the ture of them, may be used. When the extraction aromatic bases from the tea by means of a volaprocess is over and the majority of the solvent tile solvent, splitting up the theine salts in the has left the tea, the latter is subjected to a special 5 residue by means of acids, alkali or suitable salts, process to remove the rest of the solvent and any 5 extracting the theine by means of a volatile solwater it may till cont this process being vent and then saturating the theine-free prodcarri d out in su h a w y s to v i su n not with the solution of aromatic bases. Teathe tea to temperatures or more than 65 C. (abt. leaves consisting of extremely sensitive mate- 150 Fahr). This process consists in conducting rials, such a treatment would cause so great an hro h he t av after the extraction D 10 .alteration in their taste and aroma that this ess warm air or warm inert gas, thi b i n a P ss could not lead to any satisfactory result. reduced air pressure if necessary. This treat- Furthermor no satisfactory tea poor i theine ment is repeated once or several times after the can be producedby a further known process. in tea has been well moistened with water. Hereby which the extraction of the aromatic bases and i is imp ha th mperature should not 15 the theine are effected in a centrifugal machine, exceed (149 Fahr) d Preferably C- aiter which the aromatic bases are freed from (140 J- In this W y a solvents such as theine and given back to the theine-free residues. benZOle, W boiling Points a v C-, can be As the extraction takes place from the dry leaves ully r moved. v it is not possible to remove all the theine, be- T carry O h inv ntion the tea-leaves are 20 sides which the quality of the tea is greatly into be well moistened with water. Then they are fiugnced, to be extracted with methylene dichloride CHzClz Though one might expect to be able to extract h selvent, which n be o at room temthe theine from the tea by treating it with one perature or by slight y heatin e s vent. In of the well-known alkaloid solvents and though 2 /2 to 3 hours the major of the theine as been 25 in the production of cafieine-free-cofiee from the e tra ted; e theine contents a then y raw coffee been the extraction is done with suit-- about .1%. If the process of extraction is then able solvents, the coflee beans being first treated continued for a comparatively short time the with high-pressure steam or soaked inwater for whole of the theine is extracted. The solvent is some length of time,it by no means a selfthen separated from the tea-leaves and the lat- 30 evident fact that tea ccuid be freed from theine ter heated to cause the majority of the methylene by this same process, because it has quite differ-. dichloride CI-IzClz to evaporate. When this has ent properties and a process suitable for the been done warm air is passed through the tea.- treatment of coffee would never lead to a useful leaves for some time, but so that they are not result, heated beyond 65. Then the tea-leaves are 35 A very material factor is that the tea must again moistened with water and warm air once be treated in such a manner as to avoid alteramore passed through them under the same condition in its taste or its outward appearance. In tions as before, till the tea is quite dry. particular it is of great importance that the Ir solvents such as benzole are used, which leaves should retain their natural reddish-brown cannot be evaporated at 60 to 65 C., the solvent 40 colour after cooking, and this would not be the is separated from the tea-leaves only by mechancase, for example, it the tea were dried without ical means, after which warm air is passed special precautions, even at a low temperature. through. In such cases it is necessary for the In such a case the leaves would assume .a darker tea to be moistened with water several times, say

colour after eOO E. a d s greatly m shes two or three times, during the removal of the 45 the value of the-tea- I V solvent, in order to drive oil. thesolvent entirely.

It h nOW been IOund that tea can be rendered Having now described my invention, what I entir y or almost entirely free from theme wi hclaim as new and desire to secure by Letters Patout detrimental eflects if done in the following ent, is:

5omanner. l. The process of producing tea in the usual First of all the tealeaves are well moistened y leaf form suitable for infusion but containwith water and then subjected to an extraction ing less than its original theine content, which process, a solvent being used which boils at a consists in first moistening the tea leaves with low temperature. For this purpose one 01 the cold water, subjecting said leavesto the action of ll well-known o v n h as methylene l an organic solvent of theme, removing the greater 66 part of said solvent and finally removing the remainder of said solvent by the action of heated gaseous fluid, said leaves being moistened with water at least once during said final removal stage.

2. The process of producing tea in the usual dry leaf form suitable for infusion but containing less than its original theme content, which consists in first moistening the tea leaves with cold water, subjecting said leaves to the action of an organic solvent of theine such as methylene dichloride which does not appreciably affect the aromatic constituents of the leaves, removing the greater part oi. said solvent by heat and finally removing the remainder of said solvent by the action of heated gaseous fluid while maintaining said leaves at a temperature not exceeding about 65 degrees C., said leaves being again moistened with water at least once 'during said final removal stage.

3. The process of producing tea in the usual dry leaf form suitable for infusion but containing less than its original theine content, which consists in first moistening the tea leaves with water without producing an infusion thereof, subjecting said tea leaves to the action of an organic solvent of theine for a period of not ex ceeding approximately 3 hours, mechanically removing the greater part of said solvent and finally removingthe remainder of said solvent by the action of heated gaseous fluid, while maintaining said leaves at atemperature not exceeding about 65 degrees C., said leaves being again moistened with water at least once during said final removal stage.

4. The process of producing tea in the usual dry leaf form suitable for infusion but conta1ning less than its original theine content, which consists in first moistening the tea leaves with water without producing an infusion thereof, sub- Jecting said leaves to the action of .an organic solvent of theine for a period of time insuificient appreciably to dissolve the aromatic constituents, removing the greater part of said solvent and finally removing the remainder of said solvent by passing through said leaves heated gaseous fiuid without raising the temperature of said leaves beyond about 65 degrees 0., and under a pressure less than atmospheric pressure, said leaves being again moistened with water at least once during said final removal stage.

THEODOR GRETHE. 

